1. Technical Field
The present invention, for example, relates to a fluid ejecting apparatus provided with a fluid ejecting head that ejects fluid such as ink as with an ink jet printer and the like, a fluid ejecting head control method in the fluid ejecting apparatus, and a driving waveform generating apparatus for a fluid ejecting head.
2. Related Art
According to the related art, as one of a fluid ejecting apparatus that ejects fluid, an ink jet printer provided with a recording head that ejects ink has been known (e.g., JP-A-2003-1824 and the like). In the printer disclosed in JP-A-2003-1824, a voltage with a predetermined driving waveform is applied to a piezoelectric vibrator provided for each nozzle in the recording head, resulting in ejection of an ink droplet. A driving waveform signal (a trapezoidal waveform signal) for controlling the waveform of the voltage applied to the piezoelectric vibrator is generated by a driving signal generating circuit (a waveform generator) provided in a control circuit that controls the recording head, and is transmitted to a head driving circuit in the recording head. At this time, discharge data (ejection information) representing the existence or absence of ejection from each nozzle is transmitted from the control circuit to the head driving circuit. At this time, the head driving circuit does not apply a voltage to a piezoelectric vibrator corresponding to a nozzle for which the discharge data has a value of “0”, and applies a voltage to a piezoelectric vibrator corresponding to a nozzle for which the discharge data has a value of “1”, thereby selecting a nozzle, which ejects an ink droplet, based on the discharge data.
Further, the control circuit receives a pulse signal (encoder pulse signal) from an encoder that detects a relative position between the recording head and a recording medium (a target). Then, the driving waveform signal generating circuit in the control circuit transmits (outputs) a driving waveform signal in each period proportional to a pulse period on the basis of the encoder pulse signal. Further, the control circuit transmits a print timing signal generated from the encoder pulse signal to the recording head, thereby controlling ejection of the recording head based on the driving waveform signal and the discharge data at the timing synchronized to the print timing signal. In addition, in the printer disclosed in JP-A-2003-1824, one recording head is provided. However, there has been disclosed a serial printer (e.g., JP-A-2003-118136 and the like) and a line printer (e.g., JP-A-2007-69448 and the like), which are provided with a plurality of recording heads.
However, when constituting a printer provided with a plurality of recording heads, as disclosed in JP-A-2003-118136 and JP-A-2007-69448, by using the recording head and the control circuit disclosed in JP-A-2003-1824, it is necessary to provide a plurality of recording heads and a plurality of control substrates, respectively. In such a case, if the control circuit is provided in an upper level substrate, which mainly outputs an indication necessary for control, and a lower level substrate which controls the recording heads according to the indication, for example, a user-maker can set indication content depending on needs in the upper level substrate, and the lower level substrate and the recording heads can be provided as a generalized product which is common in all user-makers. Particularly, when employing a configuration in which a plurality of (M) lower level substrates are connected to one upper level substrate, the total number of substrates is reduced, so that the configuration of a recording head unit and assembly work thereof can be simplified, and the number of the lower level substrates connected to the upper level substrate can be limited to a required number smaller than M.
Further, the control circuit may be provided with a waveform designation signal transmitter that transmits a waveform designation signal for designating the waveform of the driving waveform signal. It is however preferable that the waveform designation signal transmitter is provided in the upper level substrate such that a required waveform can be appropriately set. In addition, since the driving signal generating circuit generates a driving waveform signal with a waveform designated by the waveform designation signal, it is preferred that the driving signal generating circuit is provided in the lower level substrate.
In such a case, it is necessary to transmit pulse period information of the encoder to the driving waveform signal generating circuit of the lower level substrate. For example, it may be possible to employ a configuration in which signal lines from the encoder are wired to the plurality of (M) lower level substrates individually. However, since M signal lines are necessary, an increase in the number of wires is inevitable. In this regard, there has been proposed a configuration in which the signal lines from the encoder are connected to the upper level substrate, and a timing signal, which has the same period as that of the encoder pulse signal or has a pulse period proportional to that of the encoder pulse signal, is transmitted from the upper level substrate to the plurality of lower level substrates. However, even in such a configuration case, timing signal lines for transmitting M timing signals are required between the upper level substrate and the plurality of (M) lower level substrates, resulting in complication of a wiring structure and assembly work due to an increase in the number of the signal lines. Since such problems occur, even if the timing signal is not transmitted from the upper level substrate including the waveform designation signal transmitter to the lower level substrate including the driving waveform signal generating circuit (waveform generator) through the timing signal lines based on the encoder pulse signal, it is desired to realize a configuration capable of indicating a generation timing of the driving waveform signal (driving waveform).